1. Field of the Invention
This invention relates to a so-called flying (speed matching type) auto-paster adapted to rotate a paper roll on standby so that a peripheral speed of the paper roll becomes substantially equal to a travelling speed of a moving paper web, and bond a front end portion of a paper web from the paper roll and the moving paper web together.
2. Description of the Prior Art
The conventional flying type auto-pasters include as an example an auto-paster disclosed in "Offset Printer" (the first edition was issued on Sept. 15, 1983 by the GATF Far East Office), page 45, left column, line 6, and described as follows.
First, an auto-paster P', the basic construction of which is, for example, as shown in FIG. 3, is provided adjacently to a paper roll support frame (spider) R' in a web feeder (not shown) with auto-paster frames 2' supported pivotably on the web feeder via a support shaft 1', the auto-paster P' being adapted to be turned forward and backward around the support shaft 1' as a fulcrum between a standby position Y' and a pasting position Z' by a auto-paster displacing means (not shown) attached to the web feeder.
A pressing member 3' and a cutter 5' are supported pivotably on the auto-paster frame 2' via support shafts 4', 6' respectively, and springs 7', 8' for respectively operating the pressing member 3' and cutter 5' are connected thereto. The pressing member support shaft 4' and cutter support shaft 6' are provided with stopper locking members 9', 10', which are adapted to engage one ends of respective bell crank type stoppers 13', 14' provided on the auto-paster frames 2 so that the stoppers 13', 14' are turned around respective pins 11', 12' as fulcrums, whereby the pivotal movements of the pressing member 3' and cutter 5' are stopped. The other ends of the bell crank type stoppers 13', 14' are opposed to the free ends of rods of respective solenoids 15', 16' fixed to the auto-paster frames 2', and, in accordance with the operations of the solenoids 15', 16', the bell crank type stoppers 13', 14' are turned around the pins 11', 12' as fulcrums to cause the stopper locking members 9', 10' and the first-mentioned ends of the stoppers 13', 14' to be disengaged from each other.
In the web feeder having the above-described auto-paster, the pasting of paper web is done in the following manner.
When the diameter of a paper roll (which will hereinafter be referred to as an old paper roll) O' from which a paper web W' is being payed out decreases and reaches a first predetermined level, a paper roll (which will hereinafter be referred to as a next paper roll) N' on standby and supported on a paper roll support frame R' is transferred to a pasting standby position (a position shown in the drawing) in accordance with the displacement of the paper roll support from R', and an auto-paster P' is displaced from a standby position Y' to a pasting position Z'. The front end portion of the next paper roll N' is provided in advance with a bonding agent B' for use in pasting the same paper web to the moving paper web W'.
The next paper roll N' which has reached the pasting standby position is rotated by a suitable next paper roll driving means D', and the acceleration of this paper roll N' is continued until the peripheral speed thereof has become substantially equal to the travelling speed of the paper web W' in motion.
When the diameter of the paper roll O' further decreases to reach a second predetermined level after the peripheral speed of the next paper roll N' has become substantially equal to the travelling speed of the paper web W' in motion, a suitable detecting means S detects the front end portion of the next paper roll N' or the position of the bonding agent B' provided thereon, and outputs a pasting signal.
In accordance with this pasting signal, the pressing member 3' in the auto-paster P' is operated to press the paper web W' in motion against the outer circumferential surface of the next paper roll N'. In this mechanism, the solenoid 15' is operated to turn the stopper 13'. Consequently, the stopper 13' and stopper locking member 9' are disengaged from each other, and the pressing member 3' is turned around the pressing member support shaft 4' due to the force of the operating force applying means 7' to press the paper web W' in motion against the outer circumferential surface of the next paper roll N'.
The paper web W' in motion then continues to move, and the next paper roll N' continues to rotate. As a result, the front end portion of the next paper roll N' reaches the position in which the paper web W' in motion is pressed, and it is pasted on the paper web W' in motion with the bonding agent B' provided on the front end portion of the next paper roll N'.
The cutter 5' in the auto-paster P' is then operated to cut the paper web W' in motion in a position which is closer to the old paper roll O' than to the position in which the front end portion of the next paper roll N' is bonded to the paper web W' in motion. In this mechanism, the solenoid 16' is operated to turn the stopper 14'. Consequently, the stopper 14' and stopper locking member 10' are disengaged from each other, and the cutter 5' is turned around the cutter support shaft 6' due to the force of the operating force applying means 8' to cut the paper web W' in motion.
This completes the paper pasting operation, and the auto-paster P' is displaced to the standby position Y'. Also, the next paper roll N' is released from the driving force of the next paper roll driving means D'. The pressing member 3' and cutter 5' are returned to their original positions by suitable means (not shown) while the auto-paster P' is displaced to the standby position.
What is disclosed in Japanese Utility Model Publication No. 9922/1976 will be described below as another example of a prior art flying type auto-paster.
According to this example, the process of displacement of an auto-paster from a standby position to a pasting position is different from that in the above-described example shown in FIG. 3, and an auto-paster displaying means consists of a dual air cylinder with a hydraulic cylinder connected to the auto-paster, the dual air cylinder and hydraulic cylinder of the auto-paster are interlocked.
When the diameter of an old paper roll in this arrangement decreases to a first reference level, one air cylinder member of the dual air cylinder is operated to displace the auto-paster to a pasting preparation position which is between a standby position and a pasting position and closer to the pasting position. The other air cylinder member of the dual air cylinder is operated in accordance with a pasting signal outputted after the diameter of the old paper roll has decreased to a second reference level, to displace the auto-paster speedily from the pasting preparation position to the pasting position and operate a brush which constitutes the pressing member, whereby the paper web in motion is pressed against the outer circumferential surface of the next paper roll to carry out a paper pasting operation.
During this paper pasting operation, the hydraulic cylinder and dual air cylinder are interlocked with each other, and a bouncing phenomenon of the auto-paster occurring when the auto-paster is displaced speedily from the pasting and stopped therein is prevented and offset by a hydraulic pressure exerted on this hydraulic cylinder.
After the paper web in motion has been pasted, it is cut to complete a paper pasting operation, and this final step is identical with that in the example shown in FIG. 3.
The second conventional flying type auto-paster described above is used in practice mostly in the case where the traveling speed of the paper web is high. An operation for pressing the paper web in motion against the outer circumferential surface of the next paper roll by the pressing member, which is adapted to be operated in accordance with a pasting signal outputted from a detecting means when it has detected the front end portion of the next paper roll in rotary motion or the bonding agent provided on this portion of the paper roll, has to be carried out before the arrival of the bonding agent at the position of the starting of the operation of the pressing member after the operation of the detecting means, so that this paper web pressing operation is carried out speedily.
Therefore, the pressing member pressing the paper web in motion against the outer circumferential surface of the next paper roll during this operation bounces due to a reaction force of the next paper roll occurring in response to the pressing force of the pressing member. Consequently, it takes a considerable period of time as shown in FIG. 4b before the pressing member stops with its pressing force properly stabilized, and the level of the force thereof with which the paper web in motion is pressed against the outer circumferential surface of the next paper roll becomes uneven during this time. As a result, a timing of arrival of the bonding agent at the position in which the pressing member operates and the bouncing condition of the pressing member may result in imperfect or unsuccessful bonding of the paper web in motion and the front end of the next paper roll to each other.